N,n&#39;-piperazino bis-sulfenamides



Patented July 10, 1951 UNITED STATES RATENT OFFICE.

The Firestone Tire & Rubber Company, Akron, Ohio, a corporation of Ohio No Drawing. Original application April 9, 1945 Serial No. 587,439.

Divided and this application November 2, 1949, Serial No. 125,153

4 Claims. 1

This invention relates to new compounds which are accelerators of the vulcanization of rubber. This application is a division of my copending application Serial No. 587,439, filed April 9, 1945, now Patent No. 2,514,181.

The new compounds are N,N'-dialkylene bissulfenamides of the group consisting of the bisthiazyl sulfenamides, the bis-thiazolinyl sulfenamides, and the bis-thiocarbamyl sulfenamides. The dialkylene amino groups are preferably of the piperazine type obtained by carrying out the reaction with a piperazine, either an unsubstituted piperazine or a substituted piperazine, such as methyl piperazine or 2,5-dimethyl piperazine, etc.

The new products which are accelerators are represented by the general formula:

Imidazolidine The compounds of this invention may be obtained by any usual method of preparing the sulfenamides. The following examples are illustrative:

Example 1 A solution of grams of Z-mercaptobenzothiazole was prepared with 5.5 grams of sodium hydroxide in 100 to 200 cc. of water. The solution of sodium mercaptobenzothiazole was filtered and to it was added 46.4 grams of piperazine hexahydrate. The solution was diluted somewhat, and

while being cooled and stirred, it was treated with 15.2 grams of iodine in dilute aqueous potassium iodide solution. The first precipitate was colored and poor, and this was filtered off and discarded. After adding an additional 23.2 grams. of piperazine hexahydrate, further oxidation produced a whiteor cream-colored solid. This was in part pasty, and when dry, it melted over a wide range from to C. and up. It was obviously a mixture of products containing the desired bissulfenamide. On repeated recrystallization, a product melting at 190 to 192 C. is obtained.

Analysis-Found: N=13.4; 8:30.65. Calculated for N,N'--piperazino bis(benzothiazyl sulfenamide): N=13.45; 5:30.75.

Example 2 A solution of the sodium salt of Z-mercapto 4,5-dimethyl thiazole was prepared from 7.5 grams of the mercaptothiazole and 4.74 grams of sodium hydroxide in several hundred cubic centimeters of water. This was filtered, and to it were added, first, 50 grams and then another 50 grams (total=100 grams) of piperazine hexahydrate. The solution was cooled and stirred while 13.15 rams of iodine in aqueous potassium iodide was slowly added. A cream-colored, finely divided solid was formed. This melted at 140 to C. On purification a product melting at 153.5 to 154 C. is obtained.

Analysis-Found: N=15.4; S=34.7. Calculated for N,N'-piperazine bis(4,5-dimethyl thiazyl sulfenamide): N=15.2; S=34.4.

Other accelerators of the invention include: N,N-piperazine bis (4-methyl thiazyl sulfenamide) N,N-2,5-dimethy1 piperazine bis(4-ethyl thiazyl sulfenamide) N,N-piperazine bis (dimethyl thiocarbamyl sulfenamide) N ,N'-piperazine bis (thiazolinyl sulfenamide) N,N'-trimethylene ethylene diamine bis(benzothiazyl sulfenamide) N ,N-imidazolidine bis (benzothiazyl sulfenamide) N,N-piperazine bis(benzothiazyl sulfenamide) and N ,N-piperazine bis(4,5-dimethyl thiazyl sulfenamide), prepared according to the above two examples, were tested as accelerators of rubber and compared with N-cyclohexyl benzothiazyl 4 sulfenamide as a control, by first compounding It is seen that these compounds are excellent them according to the following formula: delayer-action accelerators.

What I claim is: Parts by Welght 1. A sulfenamide of the formula Rubber 100 5 Sulfur 3 R2C R2\ Stearic acid 1.10 XS N N S X Zinc Oxide 5 011 .433 Accelerator 0.75

wherein R is selected from the group consisting These stocks were cured at dlfferent temperaof hydrogen and methyl radicals and X is tures for difierent periods of time with the follected frgm t group cgnsistjhg of thiazyl lowin results: thiazolinyl and thiocarbamyl radicals.

2. A N,N'-piperazino bis-thiazyl sulfenamide. 600% us Tensile t Break 3. N,N' piperazino bis(benzothiazyl sulfen- Cured at 240 F. amide) 40 120 30 so 120 4. N,N-piperazine bis(4.,5-dimethyl thiazyl sulfenamide). control u 00 4,150 GEORGE E. P. SMITH, JR. l e2 222 Exam REFERENCES CITED The following references are of record in the 000% Modulus Tensile at Break file of this Patent? ggs UNITED STATES PATENTS 20 40 00 20 40 60 100 5 Number Name Date 2,024,605 Sebrell Dec. 17, 1935 ,'ll;l;l:::: 11??? 33% til-28 iii; 3:??? 3:523 3122?, 312%?) 2 271 4 r Feb. 3 1942 Example 2... 525 1,775 2,150 1.800 2,700 3,450 3,075 3,075 2,435,550 Aeschnmann et a1 001L251 1949 30 FOREIGN PATENTS The times of cure are given in minutes immediately below the Modulus and Tensile headings in Number Country Date the above tables. 732,922 France Mar. 15, 1932 

1. A SULFENAMIDE OF THE FORMULA 